explain why the greatest common factor of two numbers is sometimes 1
So if you have the numbers 6 and 5
Factors of 5 : 1 , 5
Factors of 6 : 1 ,2 , 3 , 6
The only number that you see repeated in both of the factors is 1, so the greatest COMMON factor is 1.
I hope this helped if you still don't get it, message me and i'll try to explain it again!
some numbers are prime and don't have any other factors only one and itself